The processes of concentration of dilute solutions of sulfuric acid (H2SO4), in particular hydrolytic sulfuric acid for the production of pigment titanium (IV) oxide, were analyzed. It is proposed to concentrate solutions of Н2SO4 by evaporation in direct contact of acid droplets with hot industrial exhaust gases. The mathematical model of the evaporation of Н2SO4 drops in a hot gas stream, which used for the calculations, makes it possible to calculate the mass, temperature, velocity, and coordinates of the drop at any time with sufficient accuracy. However, the calculations are difficult, cumbersome and require multiple processing of large data sets. Therefore, the aim of the article was to approximate the calculated technological parameters of sulfuric acid droplet evaporation by obtaining simple mathematical dependencies. The mathematical dependences of the mass transfer coefficient and the distance traveled by a drop of Н2SO4 during evaporation on air temperature and drop diameter were obtained. It has been established that technologically expedient evaporation of Н2SO4 drops with a diameter of ≤ 0,5·10-3 m in traditional devices leads to significant droplet loss, increased corrosion of equipment, etc. So, in order to practically implement the technology of evaporation of HSA solutions with industrial exhaust gases, it is necessary to change the technological mode of operation of the evaporator and the design of the main device. It is proposed to use the obtained results to study the methods of intensification of the evaporation process, selecting a modern mass transfer apparatus, developing a technology for utilizing hydrolytic sulfuric acid and producing pigment titanium (IV) oxide.